The spine is critical in human physiology for mobility, support, and balance. The spine protects the nerves of the spinal cord, which convey commands from the brain to the rest of the body, and convey sensory information from the nerves below the neck to the brain. Even minor spinal injuries can be debilitating to the patient, and major spinal injuries can be catastrophic. The loss of the ability to bear weight or permit flexibility can immobilize the patient. Even in less severe cases, small irregularities in the spine can put pressure on the nerves connected to the spinal cord, causing devastating pain and loss of coordination.
Surgical procedures on the spine often include the immobilization of two or more vertebra. Immobilizing the vertebrae may be accomplished in many ways (e.g. fixation plates and pedicle screw systems). One of the most common methods for achieving the desired immobilization is through the application of bone anchors (most often introduced into the pedicles associated with the respective vertebra to be fixed) that are then connected by rigid rods locked to each pedicle screw. Once immobilized, the patient's bone will ideally grow between the immobilized vertebrae, creating a permanent stable boney structure. In addition to the bone anchor construct, interbody implants are often deposited in the disc space to restore and maintain the height of the disc space while fusion occurs and to provide a scaffold for bone growth.
Compression across an interbody implant promotes bone growth and fusion. Such compression is often achieved using specialized tools, as is known in the art. When performing less invasive spinal surgical procedures (e.g., one or two level transforaminal lumbar interbody fusion (TLIF) and posterior lumbar interbody fusion (PLIF), it can be difficult for the surgeon to achieve robust compression due to limited exposure of the vertebral surfaces and the use of small incisions. Some compressors sacrifice strength in order to increase visualization, resulting in flimsy arms which can flex and deliver inferior compressive load. Others increase strength but diminish visualization, making instrument attachment a challenge. Still others have a tubular counter-torque as a fulcrum point to provide a robust compression platform, but also require the user to hold the compression until a lock screw is delivered (often requiring a second person) to hold the compression.
There is a need in the art for an instrument that can deliver high compression loads without sacrificing the visibility of the surgical site, and which further can be used without the need for second or additional persons working in the incision.